Internal combustion engines may be used in a variety of applications to provide motive power, for example, to move machinery or to generate electrical power. Even within a single application, however, engines may operate under widely varying conditions. For example, a mining truck at one work site may climb uphill in an unloaded state but travel downhill carrying a full load of material. At another site, a similar mining truck may go downhill in an unloaded state but return uphill in a fully loaded state. Thus, similar engines in the two mining trucks may have vastly different performance requirements while travelling uphill or downhill. As a result, similar engines may require different engine settings to optimize engine performance during use.
Internal combustion engines generate exhaust as a by-product of fuel combustion within the engines. Engine exhaust contains, among other things, unburnt fuel, particulate matter such as soot, and gases such as carbon monoxide or nitrous oxide. Regulatory agencies have imposed limits on the maximum amounts of exhaust emissions that an engine may release into the atmosphere during operation. Modern engines must, therefore, deliver optimum performance without exceeding the emissions limits imposed by the emissions control regulations. Typically, an engine manufacturer provides an engine to an end user with a default calibration parameter set, which specifies default values for various control parameters for the engine. The engine manufacturer determines the default values based on an expected use of the engine. Although the default calibration parameter set may ensure compliance with emissions control regulations, an engine operating with the default calibration parameter set may not be fully optimized for the actual usage cycle.
One attempt to address some of the problems described above is disclosed in U.S. Pat. No. 6,965,826 of Andres et al. issued on Nov. 15, 2005 (“the '826 patent”). In particular, the '826 patent discloses an electronically controlled internal combustion engine in which a plurality of different engine control calibration algorithms are made available to an engine control system. The '826 patent explains that each control calibration algorithm corresponds to a particular duty cycle while being optimized for a performance parameter such as reduced emissions under a variety of constraints. The '826 patent discloses that an operator can choose from among several different available duty cycles for the machine and that the control system selects a control calibration algorithm corresponding to the selected duty cycle. The '826 patent also discloses an embodiment where a duty cycle determiner predicts a future duty cycle based on historical engine operation data. The control system of the '826 patent selects a control calibration algorithm based on the predicted duty cycle. Further, the '826 patent discloses an embodiment in which the control system determines a control calibration algorithm for a predicted duty cycle by optimizing a particular performance parameter under known constraints, such as, emissions regulations and customer specific requirements.
Although the '826 patent discloses selection of a control calibration algorithm based on duty cycle, the disclosed system may still be less than optimal. In particular, the system of the '826 patent selects from control calibration algorithms optimized for a single performance parameter such as reduced emissions. These algorithms, however, may still not provide optimal engine operation, for example, by simultaneously reducing emissions and fuel consumption. Further, the duty cycle predictor of the '826 patent selects a duty cycle that provides the best match between the historical engine operation data and predetermined duty cycles. The system of the '826 patent then selects or determines a control calibration algorithm for the predicted duty cycle. Selecting the control calibration algorithm based on historical operation data and limiting selection of the control calibration algorithm to one of the predetermined duty cycles may be sub-optimal because actual engine operation may differ significantly from the predicted duty cycle. For example, as discussed earlier, even when a machine performs the same operation (e.g. mining), an engine associated with the machine may still have widely varying performance requirements based on the terrain over which the machine operates. Thus, relying on historical engine performance data may not yield optimal engine performance. In addition, determining a control calibration algorithm by optimizing a particular performance parameter may not be feasible if the control system has limited processing capabilities.
The engine system of the present disclosure solves one or more of the problems set forth above and/or other problems of the prior art.